Lithium battery upgrade N&B Flair (1 Viewer)

[andycap63]

Hi Folks,
The 3 x 160ah Mastervolt agm leisure batteries on my 2010 Flair have come to the end of their life. Ideally I'd like to replace them with 2 x Sterling 120ah lithiums (AL12120's) however I realise this is not just a straight swap.

The Sterlings will physically fit and the weight saving will be great but the charging systems will need consideration.

My existing cbe solar controller can be changed for a Victron mppt with a lithium setting.

The Mastervolt inverter/charger (mass combi 12/2000-100) doesn't have a lithium setting but speaking to Mastervolt tech dept they advise that the current! Gel setting would be okay (14.4v on bulk charge) as long as the lithiums have overcharge protection. Sterling confirmed their inbuilt BMS does provide overcharging protection.

Confusion arises over the existing split relay charging system. Sterling recommend the use of a B2B charger and I'd fit Sterlings own 1260 B2B. What do I do about the existing relay system though? It connects the positive side of both starter and hab batteries but looks like it might support other services. I'm guessing the relay in the picture is initiated by the alternator to provide charging to the hab batteries. Could I simply remove or disable the relay?

I know each installation is different but there's a very impressive knowledge base on here with several people having built there own lithium systems. I'd welcome any advice/wisdom/comments.

Thanks,
Andy.

 

[GPW]

Why don't you just fit Gel batteries?
The Mastervolt appears to favour them according to their data (i.e. they appear to test them with Gels).

 

[34127]

Is this thread of any interest.

100AH Lithium Battery £500

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[andycap63]

TBH the Mastervolts have done brilliant lasting 9 years and replacing them would be the most convenient route. I like the weight saving and usability of the lithiums though. They're happy with the big discharge rate the inverter demands (coffee maker, etc.) and they accept high charge rates via B2B which is handy when there's little or no sun. We do tend to move every few days so they would seem to suit our typical usage very well.
It might be that my current! charging system isn't suited to this newer technology though and I might be best sticking with the agm's. Just feel I should maybe spend the money on new technology rather than old.

 

[GPW]

I don't rate AGMs as they seem very easy to shorten the life of, people have much better lifetimes from Gel. Lithium is a bit untested and each one has different circuits and cells (I.e. Lithium is too broad a term to identify any characteristics apart from price and weight), and Lithium doesn't like certain things either.

For me of price vs performance I'd go with Gel, but whether I'd go for 2 (220Ah) or 3 is debatable - depends how many Ah you use per day - but 2 will be much lighter and cheaper than 3